Ionic liquid-mediated concurrent oxygen vacancies and N-doped carbon in hierarchical TiP2O7 for lithium storage

The development of high-performance TiP 2 O 7 anode materials has been fundamentally limited by their intrinsically poor electronic conductivity and slow Li + diffusion kinetics. Herein, we report an innovative ionic liquid-mediated strategy that simultaneously engineers oxygen vacancies and nitrogen-doped carbon in hierarchical TiP 2 O 7 architectures. Through pyrolysis gas reduction, oxygen vacancies are introduced into the TiP 2 O 7 lattice, promoting the formation of C P bonds and defect energy levels while broadening the lithium ions transport channels. The concurrent formation of a nitrogen-doped carbon matrix, rich in pyridinic-N configurations, establishes a highly conductive network and optimizes electrode-electrolyte interfacial dynamics. The co-engineered material delivers exceptional rate capability (301.5 and 241.7 mA h g −1 at 5 and 10 A g −1 , respectively), doubling the capacity of the ionic liquid-free counterpart. First-principles calculations elucidate the underlying mechanisms: oxygen vacancies substantially reduce the Li + diffusion barrier by 29% (from 0.42 eV to 0.30 eV), while synergistic coupling with nitrogen-doped carbon creates a 0.73 eV in-gap state that effectively boosts charge transfer kinetics. This multiscale engineering strategy, which synergistically integrates atomic-scale defect control with mesoscopic interface optimization, establishes a generalizable design principle for next-generation high-rate electrode materials.